Historically, the term microwave power module (MPM) is associated with a small fully integrated self-contained radio frequency (RF) amplifier that combines both solid-state and microwave vacuum electronics technologies. Typically, the output power of these MPMs is on the order of about 100 watts CW over an octave bandwidth. Because of their smaller size and lower mass compared to conventional traveling-wave tube amplifiers, these MPMs may have applications in electronic warfare systems.
The MPMs require both a solid-state amplifier at the front end and a microwave vacuum electronics amplifier at the back end. However, such MPMs cannot be utilized for communications because the MPMs are not optimized for linearity or efficiency. Also, the MPMs can be very expensive to manufacture, particularly when modules are produced in very small quantities for space applications. Also, a kilovolt (kV) class power supply is required to power the traveling wave tube amplifier, which is a part of the microwave vacuum electronics.